Submission #1126874

#	Time	Username	Problem	Language	Result	Execution time	Memory
1126874		Halym2007	Pipes (BOI13_pipes)	C++17	0 / 100	6 ms	5224 KiB

pipes

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define sz size()
#define ff first
#define ss second
#define pb push_back
#define pii pair <int, int>
#define dur exit(0)
#define dur1 return(0)
const int N = 2e5 + 5;
ll n, m, val[N], jog[N];
pii par[N];
vector <pii> v[N]; 
vector <int> order;

void dfs (int x, int p) {
	for (pii i : v[x]) {
		if (i.ff == p) continue;
		dfs (i.ff, x);
		par[i.ff] = {x, i.ss};
	}
	order.pb (x);
}

int main () {
	freopen ("input.txt", "r", stdin);
	ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin >> n >> m;
	assert (n - 1 == m);
	for (int i = 1; i <= n; ++i) {
		cin >> val[i];
	}	
	for (int i = 1; i <= m; ++i) {
		int l, r;
		cin >> l >> r;
		v[l].pb ({r, i});
		v[r].pb ({l, i});
	}
	dfs (1, -1);
//	for (int i : order) {
//		cout << i << " ";
//	}
//	return 0;
	order.pop_back();
	for (int i : order) {
		val[par[i].ff] -= val[i];
		jog[par[i].ss] = val[i];
	}
	if (!val[1]) {
		for (int i = 1; i <= m; ++i) {
			cout << jog[i] + jog[i] << "\n";
		}
	}
	else cout << "0";
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:27:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         freopen ("input.txt", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 30
• Subtask 2: 0 / 70